Takayasu arteritis (TA) is a rare, sporadic and chronic inflammatory arteritis, which predominantly affects the aorta and its branches. Diagnosis can be difficult and there are limitations to the current diagnostic work-up. By detecting areas of active glucose metabolism present in active vasculitis, imaging with fluorine-18 fluorodeoxyglucose positron emission tomography ((18)F-FDG PET) could potentially have a role in the management of TA. Our aim was to assess this role by reviewing 28 (18)F-FDG PET scans performed on 18 patients suspected of having TA. All patients had full clinical and laboratory assessment, cross-sectional imaging and angiography, and 16/18 satisfied the American College of Rheumatologists' criteria for TA. (18)F-FDG PET achieved a sensitivity of 92%, a specificity of 100%, and negative and positive predictive values of 85% and 100% respectively in the initial assessment of active vasculitis in TA. We conclude that (18)F-FDG PET can be used to diagnose early disease, to detect active disease (even within chronic changes) and to monitor the effectiveness of treatment.